1. Field of Technology
The present invention relates to a decentralized solution of microscopic particles including nano-particle clusters and to a circuit formation device by using the decentralized solution of microscopic particles.
2. Background of Art
A conventional general method of forming arbitrary conductive patterns on a circuit board or the like is a method in which lithography technology, etching technology, and plating technology are combined. This method requires a mask for exposure that needs much time in designing and preparation as well as advanced machining technique. In addition, since a series of processes are complex, a long preparation time is needed, resulting in a high cost. If it becomes necessary to modify the mask in, for example, limited production of a wide variety of products, a high cost, delayed delivery, and other problems occur. The use of large quantities of materials hazardous to the environment, such as resists and etching solutions, is indispensable, so extra costs have been needed in management and processing of waste materials.
In other proposed conductive pattern forming methods in which processes are simple, printing processes that use a conductive microscopic particle decentralized solution, in which conductive microscopic particles, binder resin, and other materials are decentralized in a solvent, are used; the printing processes include a screen printing process, a dispenser printing process, an ink jet printing process, and an electrophotography process. These methods achieve simple processes because of less steps, use less materials, and produces less waste materials, so they are expected as processes that greatly reduces costs.
In the printing processes in which conductive patterns are formed by using a conductive microscopic particle decentralized solution in which conductive microscopic particles are decentralized, however, distances among microscopic particles in the conductive microscopic particle decentralized solution become large. As a result, when conductive wires are formed by, for example, heating, many voids are generated and thereby the wires become more resistive and are weakened in strength. To reduce the heating temperature when wires are formed, nano-scale microscopic particles having a property for reducing a melting point may be used in the conductive microscopic particle decentralized solution used in the printing process. In this case, however, the primary particle diameters of the above nano-scale microscopic particles are small, so the thickness of a film formed in one printing is small. To achieve the desired wire film thickness, films have to be laminated by repeating patterning, which may reduce the productivity.
To address these problems, a method was studied in which clustered conductive microscopic particles, for example, are used to reduce the resistance by shortening the distances among the conductive microscopic particles in advance (Patent Document 1).
Patent Document 1: Japanese Application Patent Laid-open Publication No. 2003-288812